Fixing agent in the form of an oil/water type emulsion or suspension, and preparation of the same

ABSTRACT

A fixing agent in the form of an oil/water type, lamellar emulsion or suspension in which the aqueous phase is the principal component, the aqueous phase containing water and a byproduct of agriculture or fermentation and the oil phase containing oil and emulsifiers. The emulsion or suspension is prepared by adding an aqueous solution to the oil phase in order to produce a water/oil type emulsion or suspension, by adding a portion of the aqueous phase in order to produce an inverse oil/water type emulsion or suspension, and by thereafter mixing the oil/water type emulsion or suspension with the remainder of the aqueous phase.

BACKGROUND OF THE INVENTION

The invention relates to a fixing agent in the form of an oil/watertype, lamellar emulsion or suspension, which fixing agent can be usedfor fixing a fertilizer powder to the surfaces of plant seeds. Theinvention also relates to a method for preparing such a fixing agent.

The rapidity with which the roots of a plant reach the fertilizer hasgreat significance for the ability of the plant to take up the nutrientspresent in the fertilizer and for the success of the initial developmentand growth of the plant in the first three weeks.

The quantities of the principal nutrients (N, K, P, Ca, S, Mg) passingfrom fertilizers into plants, i.e. the efficiency of the nutrients,usually vary from a few percent to 70-80 percent. The efficiency ofphosphorus in particular is low, approx. 5-20%. The efficiencies oftrace elements (B, Co, Cu, Fe, Mn, Mo, Zn, Cl) are often even lower thanthis.

The method by which the fertilizer is spread, i.e. how far from the seedthe fertilizer is deposited, affects the ability of the plant to utilizethe nutrients. The nutrients in a fertilizer deposited far from theseed, for example at a distance of 6 cm from it, may have time to reactwith soil minerals and to form poorly soluble compounds even before theroots of the plant have reached the location of the fertilizer.

When, for example, phosphorus fertilization is carried out, as describedabove, by conventional broadcasting of the fertilizer on the soilsurface or by mixing it into the surface layer of the soil, thephosphorus efficiency is 5-10%. If the fertilizer is spread by rowapplication or tape application at a specified distance from the seed,the phosphorus efficiency is approx. 10%.

A somewhat better phosphorus efficiency is achieved when the phosphorusfertilizer is deposited in the immediate vicinity of the seed or whenthe seed is coated with the fertilizer. In this case the efficienciesare, respectively, 15% and 20%.

The coating of plant seeds for various reasons has long been a knowntechnology. There are different surface treatments, beginning from thesimple and conventional seed dressing with biocides to combat plantdiseases and noxious insects. In this case the seeds as such are treatedwith a fine-ground active agent or a powder mixture containing it, orthe active agent is dissolved or slurried in a suitable solvent, oftenwater or an organic solvent, and the seeds are then treated with theobtained solution or slurry.

From patent publication U.S. Pat. No. 4,761,423 there is known a wetseed dressing method wherein the seeds are impregnated with an emulsionthat contains water, oil, an emulsifier and a biocide.

Coating of seeds has also been used for delaying the germination ofseeds. Polymers have been used as fixing agents also in the coating ofseeds with substances having other effects. Coating may, for example,improve the ability of the seeds to withstand drought, heat, soilsalinity, or other external stress factors.

With the help of coating, for example, lightweight seeds of rice can berendered heavier, whereupon they will not be so easily carried by wateror wind; see, for example, patent publication U.S. Pat. No. 4,192,095.

It is also generally known to add nutrients to a coating in order topromote plant growth.

Grass seeds have been treated with, for example, lime or talc in orderto ensure the establishment of a lawn (Scott 1975). The coating of seedswith nutrients is discussed in several studies (e.g. Heydecker andCoolbear 1977, Rebafka et al. 1983, Scott et al. 1987). The greatestproblems have been a poor germination percentage of the seeds,especially when oil has been used as the fixing agent, and poorattachment of nutrients to the seed surface when aqueous solutions havebeen used.

A great deal of research has been conducted in order to solve theseproblems. Various fixing agent compositions have been experimented withfor the fixing of nutrients or other growth-promoting substances orcompositions to the surfaces of plant seeds.

In particular, the usability of various polymers has been experimentedwith. It is, for example, a known method to coat seeds withwater-soluble polymers such as starch, methyl cellulose and gum arabic.The greatest disadvantage is the large amount of water associated withthe use of these polymers. The handling of a large amount of waterrequires special apparatus, and the coating process is slow. In order toprevent the wetting of the seeds, the seeds must often be dried at a lowtemperature. The above-mentioned polymers often form a hard, easilybreaking coat around the seeds.

Patent publication WO 9325078 describes a composition used for thecoating of seeds, which composition contains a polysaccharidehydrolysate, for example, carboxymethyl cellulose or carboxymethylstarch hydroxylate. The aqueous solutions of these may also be sprayedin the form of relatively concentrated aqueous solutions (30%) onto theseed surfaces.

The use of water-insoluble polymers, on the other hand, usually requiresthe use of an organic solvent, in which case a large solvent amount maypromote the penetration of the polymer into the seed. It is alsopossible to use aqueous suspensions of these polymers for the treatmentof seeds. For example, CA PLUS 112:17756 (PL 146138) and CA PLUS122:49097 (PL 159474) describe such an application.

Patent publication U.S. Pat. No. 4,251,952 describes seeds coated with amixture of a water-insoluble polymer and sugar. The polymers used arevarious commercial poly- or copolymers.

From unpublished patent application FI 19992768 (Kemira Agro Oy) thereis known a composition intended for the surface treatment of seeds, thecomposition comprising a fixing agent layer made up of an oil/wateremulsion and a layer of fertilizer powder. The fixing agent mixture usedfor forming the fixing agent layer may also contain a fluid byproduct ofagriculture or fermentation.

In addition to the disadvantages already stated above, the prior-knownmethods may also have the disadvantage of stickiness of the coated seedsurfaces, causing the seeds to stick together and giving the seeds poorflow properties. The apparatus required for the handling of the seedsalso becomes easily soiled. A coating too moist, for its part, may causepremature germination of the seeds. The prior-known methods also havethe disadvantage of incomplete or non-uniform adhesion of the activeagent to the seeds and/or its poor retention on seed surfaces.

SUMMARY OF THE INVENTION

According to the present invention there is provided a fixing agent inthe form of an oil/water type, lamellar emulsion or suspension, whereinthe aqueous phase is the principal component, the aqueous phasecontaining water and a byproduct of agriculture or fermentation, and theoil phase containing oil and emulsifiers, and the fixing agent isprepared by adding an aqueous solution to an oil phase in order toproduce a water/oil type emulsion or suspension, by adding a portion ofthe aqueous phase to produce an inverted oil/water type emulsion orsuspension, and by thereafter mixing the said oil/water type emulsion orsuspension with the remainder of the aqueous phase.

The said fixing agent may contain aqueous phase 50-95% by weight, oilphase 5-50% by weight, preferably aqueous phase 70-90% by weight and oilphase 10-30% by weight.

The said aqueous phase may contain water and a byproduct of agricultureor fermentation at a weight ratio of 1:4-4:1, preferably 3:7-7:3.

The fixing agent according to the invention may additionally containother ingredients, such as a preservative, e.g. potassium sorbate,and/or a stabilizing agent, which may be a pH control agent, such asphosphoric acid. Stabilization of the emulsion or suspension structureis achieved under the effect of the stabilizing agent. It is alsopossible to use organic acids, such as citric acid or oxalic acid, asthe stabilizing agent.

The said byproduct of agriculture or fermentation is preferably a fluidbyproduct of agriculture or fermentation, for example molasses, such asroot or cane molasses, vinasse or syrup, or a mixture thereof. The saidbyproduct of agriculture or fermentation may also be a solid product.The said fluid byproducts contain varying amounts of water. This wateramount is included in the amount of the said byproduct.

The said oil may be a biodegradable or readily biodegradable animal orvegetable oil or mineral oil, such as white oil, or a mixture thereof.

The said emulsifiers comprise emulsifiers suitable for this purpose. Inparticular, the said emulsifiers comprise two different emulsifiers, ofwhich one is a lipophilic emulsifier having an HLB (hydrophiliclipophilic balance) value within the range 2-8, preferably approx. 4,and the other is a hydrophilic emulsifier having an HLB value within therange 12-16, preferably approx. 15.

The amount of lipophilic emulsifier is preferably approx. 0.5-2% byweight, and especially preferably approx. 1% by weight. The amount ofhydrophilic emulsifier is preferably approx. 1.5-4% by weight andespecially preferably approx. 3% by weight. The total emulsifier amountis preferably approx. 2-6% by weight. These amounts have been calculatedfrom the weight of the final-product emulsion or suspension.

The fixing agent according to the invention can be used for fixing afertilizer powder to the surfaces of plant seeds. Owing to thecomposition and structure of the fixing agent according to theinvention, the adhesion of the fertilizer powder to seed and itsretention on the surfaces of seeds are excellent. The fixing agent mayalso contain the polymers conventionally used as fixing agents in thecoating of seeds, mentioned also in the description of the state of theart.

The size of the seeds to be surface-treated and the type of theirsurface, which are properties specific to a plant species, affect thequantity of fixing agent that is required for fixing the desired amountof fertilizer powder to the seed surface. Preferably, the fixing agentis used in an amount of 0.5-5 parts by weight per 100 parts by weight ofseeds.

According to the invention there is also provided a method for preparinga fixing agent in the form of an oil/water type, lamellar emulsion orsuspension that contains water, a byproduct of agriculture orfermentation, oil and emulsifiers, the method comprising the followingsteps:

-   i) an aqueous phase which contains water and a byproduct of    agriculture or fermentation is formed,-   ii) an oil phase which contains oil and emulsifiers is formed,-   iii) an aqueous solution is added to the oil phase in order to    produce a water/oil type emulsion or suspension,-   iv) a portion of the said aqueous phase is added to the said    water/oil type emulsion or suspension to produce an inverted    oil/water type emulsion or suspension, and-   v) the emulsion or suspension obtained from step iv) is mixed with    the remainder of the aqueous phase in order to form the desired    emulsion or suspension.

The method according to the invention preferably comprises an additionalstep wherein

-   vi) a stabilizing agent is added to the emulsion or suspension    obtained from step v).

If it is desired to incorporate a preservative into the fixing agent,the preservative is added to the said aqueous phase.

The aqueous phase added in step iii) may be mainly water or a portion ofthe said aqueous phase. The adding of the said aqueous solution may becarried out under vigorous agitation by means of, for example, aninjection pump or a homogenizer, which may be based on ultrasoundtechnology or mechanical emulsification technology. The amount of thesaid aqueous solution may be 2-10% by weight, calculated from the weightof the final product emulsion or suspension. In step iii) thetemperature of the oil phase may be 30-50° C., preferably approx. 40°C., and the temperature of the aqueous solution may be higher than this,preferably 35-55° C.

In step iv), aqueous phase is added in such an amount that in thewater/oil emulsion or suspension there occurs a phase change to theoil/water type. In this case the amount of aqueous phase added ispreferably equal to or greater than the amount of the oil phase. Thetemperature may be 30-50° C., preferably 37-45° C., and especiallypreferably approx. 40° C.

In the production method according to the invention, the forming ofwater-oil layers is ensured by preparing in the first step a water/oiltype emulsion or suspension and by inverting it in the second step tothe oil/water type. In this case the final emulsion or suspension is ofthe type oil/water, in which the aqueous phase is the principalcomponent in the medium in which the oil-water layer structures areemulsified, forming lamellar structures. For the stability of theproduct it is essential that aqueous phase-oil phase layers be produced.The obtained product is characterized in that water is bound with thehelp of emulsifiers also to the interfaces formed by oil and water. Theproduct has excellent adhesion to surfaces to be coated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLE 1 Preparationof an Oil/Water Emulsion Which Contains Molasses

-   A. A water amount which is 37% by weight of the production batch is    measured. A preservative (potassium sorbate), 0.3% by weight of the    production batch, is mixed with the water. 4% by weight of this    aqueous mixture is separated for later use, item D.-   B. An aqueous phase is prepared by heating aqueous mixture A to    50° C. and by adding molasses at room temperature (T=15-45° C.),    preferably 35° C., in an amount of 50% by weight of the production    batch. The mixture is homogenized by circulation.-   C. An oil phase is prepared by placing, in a separate vessel, white    oil in an amount of 10% by weight of the production batch. The said    oil is a colorless, odorless, catalytically hydroisomerized and    dewaxed oil that contains hydrogenated hydrocarbons high in    isoparaffins. To the oil there are added surface active components:    -   lipophilic emulsifier (HLB value approx. 4) 1% by weight of the        production batch and    -   hydrophilic emulsifier (HLB value approx. 15) 3% by weight of        the production batch.    -   The oil and the emulsifiers are mixed at 40° C. until        homogeneous.-   D. Aqueous mixture, T=45° C., from item A is added to the oil phase,    T=40° C. The amount of this aqueous mixture is 4% by weight of the    production batch. The adding of the aqueous mixture is carried out    under vigorous agitation by means of an injector pump or a    homogenizer, which may be based on ultrasound technology or    mechanical emulsification technology.-   E. Aqueous phase B is added to oil phase D in such an amount that in    the water/oil emulsion (W/O emulsion) there occurs a phase change to    the O/W type. This phase change is seen as a decrease in viscosity    after an increase. The temperature must be 37-50° C., preferably    40° C. Aqueous phase B is required in at least the same amount as    oil phase C.-   F. O/W type emulsion E is added to the remaining aqueous phase B by    cautious circulation, by avoiding any unnecessary charge of energy.-   G. Finally an acid phosphoric acid 0.3% of the production batch, is    added. The acid is first diluted in a portion of pure water (taken    into account in the total water amount) and is mixed cautiously by    circulation. Excessive energy is to be avoided. For example, when a    1000-liter batch is being prepared, 3 liters of acid is diluted in    10 liters of water.

The product prepared in the manner described above is designed inparticular for use as a binding coating for seed grain coating needs.The raw materials of the product have been selected carefullyconsidering the purity and biodegradability requirements of theagricultural and food chain.

Physical properties of product: typical limits density (15° C.)  1.1kg/m³ 1.05–1.20 kg/m³ viscosity (15° C.) 17 cSt   15–250 cSt pH  5.5 5.0–6.0 refractometer reading ATAGO N2 (28–62%) 44%   40–50%

The product is suited for being spread by spraying.

Shelf life: 4-22° C. at minimum 6 months.

EXAMPLE 2 Preparation of Oil/Water Emulsion Which Contains Molasses

The oil phase already contains the emulsifiers and 4% by weight ofwater, in which case the product is moderately resistant to freezingtemperatures and is easy to store.

The aqueous phase is prepared by adding to water potassium sorbate, 0.3%by weight, and molasses, T=40° C.

A portion of this aqueous phase is heated to a temperature higher thanthe oil phase, approx. 5° C. is a sufficient difference. The amount ofthe aqueous phase heated must be at least the amount of the oil phase involume units.

The warm aqueous phase is emulsified into the oil phase in such anamount that there is a phase change to the O/W type, in which case theviscosity begins, after a rise, to decrease when aqueous phase is beingadded.

This O/W type emulsion can, under slight agitation, be added to theremainder of the aqueous phase (mixture of water and molasses).

Finally there is added phosphoric acid, 0.3% by weight, which is dilutedwith water at a ratio of 3/10. The water used for this is taken intoaccount in the total water amount. Mixing is carried out usinglow-energy circulation.

EXAMPLE 3 Effect of Molasses Added to the Oil/Water Emulsion on theEmergence of Wheat Seeds

The effect of the molasses amount present in the oil/water emulsion,used for the surface treatment of seeds, on the emergence of wheat seedswas studied in emergence tests carried out in field soils when the seedshad been treated with emulsions containing molasses, water and oil indifferent proportions.

For purposes of the test, a series of molasses-containing oil/wateremulsions were prepared by the procedure described in Example 1. Eachemulsion contained 25% by volume (v/v) of a biodegradable oil andadditionally so much molasses that in the completed emulsions the volumeratio of oil/water to molasses was 4:0, 3:1, 2:2, 1:3 and 0:4.

For introducing the emulsion onto the seed surfaces, the seeds weretreated in a commercial test seed-dressing device (Hege). From eachsurface-treated batch of seeds, 4×100 seeds were planted to germinate ata depth of 4 cm in 1-liter plastic pots filled with field soil. Thecontrols were 100 untreated, similarly planted seeds. Each pot waswatered at fixed intervals to maintain the soil moisture constant. When11 days had elapsed from the planting, the emergence percentage wasdetermined using the standard 5.4.A.3 defined by ISTA. The effect of theamount of molasses in the oil/water emulsion introduced onto the seedsurface on the emergence of wheat seeds is shown in Table 1.

TABLE 1 Effect of the aqueous oil to molasses mixing ratio on theemergence of wheat, data in table form Test member Emergence % Untreated93 Molasses 93 Molasses:water + oil (1:3) 89 Molasses:water + oil (2:2)95 Molasses:water + oil (3:1) 94 Water + oil 81

The results show that the adding of molasses to the oil/water emulsionsignificantly promotes the emergence of wheat. Furthermore, the adhesionof fertilizer powder to seed surfaces was studied with the emulsionsaccording to the example. A molasses/oil/water emulsion fixed thefertilizer powder uniformly and better than a mere oil/water emulsion,and the technical quality was better.

EXAMPLE 4 Effect of Molasses Added to Oil/Water Emulsion on the Adhesionof Fertilizer Powder to Seeds and on its Retention on Them

For purposes of the test, a series of molasses-water solutions andoil/water emulsions were prepared. The emulsions were prepared by theprocedure described in Example 1. The oil/water volume ratio in theemulsions was 1:3.

Barley grains were treated with fixing agents in the manner described inExample 3. The grains treated in this manner were coated withmonopotassium phosphate (MKP). The amount of moistener was 2% and theamount of MKP was 8% of the weight of the grains. The test results areshown in Table 2.

TABLE 2 Test member Adhesion % Retention % Grade Untreated — — —Oil/water emulsion 100 67 Non-uniform adhesion Molasses:water 1:1 100 85Result uniform Molasses:water 2:1 100 93 Result uniform**Molasses:oil/water 100 88 Result uniform* emulsion 1:1 *)Does not clogthe seeding machine **)Sticks to the wheel of the seeding machine

The results show that the adding of molasses to the oil/water emulsionsignificantly improves the retention of the fertilizer powder on thesurface of seeds.

LITERATURE

Heydecker, W and Coolbear, P. 1977. Seed treatments for improvedperformance—survey and attempted prognosis. Seed Sci. and Technol.5:353-425.

Rebafka, F. -P., Batino, A. and Marschner, H. 1993. Phosphorus seedcoating increases phosphorus uptake, early growth and yield of pearlmillet (Pennisetum glaucum (L). R. Br.) grown on an acid sandy soil inNiger, West Africa. Fert. Res. 35: 151-160.

Scott, J. M. 1975. Effects of seed coating on establishment. N.Z.Journal of Agricultural Research 18:59-67.

Scott, J. M., Jessop, R. S., Steer, R. J. and Mclachlan, G. D. 1987.Effect of nutrient seed coating on the emergence of wheat and oats.Fert. Res. 14: 205-217.

International Seed Testing Association (ISTA). 1996. Seed Sci. &Technol. 24, Supplement. International Rules for seed testing. Zurich,Switzerland.

1. A fixing agent for fixing fertilizer to seeds, comprising: anoil/water lamellar emulsion or suspension wherein an aqueous phase isthe principal component, the aqueous phase containing water and abyproduct of agriculture or fermentation in sufficient quantities to fixfertilizer to seeds and an oil phase containing oil and emulsifiers;wherein the fixing agent contains aqueous phase 50-95% by weight and oilphase 5-50% by weight; and wherein the aqueous phase contains water anda byproduct of agriculture or fermentation at a weight ratio of 1:4-4:1.2. The fixing agent according to claim 1, further comprising apreservative.
 3. The fixing agent according to claim 1, furthercomprising a stabilizing agent.
 4. The fixing agent according to claim1, wherein said byproduct of agriculture or fermentation is molasses,vinasse or syrup, or a mixture thereof.
 5. The fixing agent according toclaim 1, wherein said oil is a biodegradable or readily biodegradablevegetable or animal oil or mineral oil.
 6. The fixing agent according toclaim 1, wherein said oil is a biodegradable or readily biodegradablevegetable or animal oil, white oil, or a mixture thereof.
 7. The fixingagent according to claim 1, wherein the fixing agent contains aqueousphase 70-90% by weight and oil phase 10-30% by weight.
 8. The fixingagent according to claim 1, wherein the aqueous phase contains water anda byproduct of agriculture or fermentation at a weight ratio of 3:7-7:3.9. A fixing agent for fixing fertilizer to seeds, comprising: anoil/water lamellar emulsion or suspension that fixes fertilizer toseeds, an aqueous phase being the principal component thereof, saidaqueous phase containing water and a byproduct of agriculture orfermentation at a weight ratio of 1:4-4:1, and an oil phase containingoil and emulsifiers, wherein the fixing agent contains the aqueous phaseas 70-90% by weight and the oil phase as 10-30% by weight.
 10. Thefixing agent according to claim 9, further comprising a preservative.11. The fixing agent according to claim 9, further comprising astabilizing agent.
 12. The fixing agent according to claim 9, whereinsaid byproduct of agriculture or fermentation is molasses, vinasse orsyrup, or a mixture thereof.
 13. The fixing agent according to claim 9,wherein the aqueous phase contains water and a byproduct of agricultureor fermentation at a weight ratio of 3:7-7:3.
 14. A fixing agent forfixing fertilizer to seed, comprising: an oil/water lamellar emulsion orsuspension wherein an aqueous phase is the principal component, theaqueous phase containing water and a byproduct of agriculture orfermentation, selected from molasses, vinasse or syrup, or a mixturethereof, in sufficient quantities to fix fertilizer to seeds, and an oilphase containing oil and emulsifiers, wherein the aqueous phase containswater and the byproduct of agriculture or fermentation at a ratio of 1:1to 3:7 of water to agricultural byproduct.
 15. The fixing agentaccording to claim 14, wherein the aqueous phase contains water and thebyproduct of agriculture or fermentation at a weight ratio of 1:1.